Sterols

9,11-Secosteroids are biologically active secondary metabolites from the marine invertebrate, Pseudopterogorgia americana. They are produced in vitro through an incubation of the steroid substrate with a cell-free extract of P. americana containing the necessary enzymes. Further optimization of this incubation was attempted through adjustment of incubation reagents and cofactors. The enzymes responsible for secosteroid production were partially purified through chromatography in an effort to isolate and purify these enzymes. Finally, experiments with radiolabeled gorgosterol led to the elucidation and isolation of a key secosteroid precursor, 9,11-dihydroxygorgosterol.

Chemical analysis of large number of specimens of the sponge Xestospongia muta have revealed the existence of three distinct sterol chemotypes. Since sponges are well known to contain a diverse array of all classes of lipids, the utility of fatty acid composition as a chemotaxonomic tool for Xestospongia muta has been addressed. Further the biosynthetic capabilities of the three chemotypes are being evaluated for possible taxonomic use. Further the utility of TLC and NMR as additional taxonomic tools has also been evaluated.

A-nor sterols have been isolated and characterized from the marine sponge Teichaxinella morchella using High Performance Liquid Chromatography, Nuclear Magnetic Resonance, and Mass Spectrometry. A cell free extract of T. morchella was used to determine the biosynthetic origin of the sterols. Incubation experiments with radiolabled Farnesyl Pyrophosphate and cholesterol showed that the sterols are coming from a dietary source. Subcellular localization studies showed that the sterols are part of the cell membrane.